Intro to Bones + Soft Tissue Flashcards
1
Q
What is a joint?
A
point at which 2 separate bones meet
2
Q
What is the muscoskeletal system made up of?
A
- bone
- muscle
- connective tissue
3
Q
What are the 3 different types of connective tissue?
A
- tendon
- ligament
- cartilage
4
Q
How many bones in an adult skeleton?
A
206
5
Q
How many bones in a child?
A
270
6
Q
What are the 2 main parts of the skeleton?
A
Appendicular + Axial
7
Q
What is a part of the axial skeleton?
A
- cranium
- vertebral column
- ribcage
8
Q
What is a part of the appendicular skeleton?
A
- pectoral girdle
- upper + lower limbs
- pelvic girdle
9
Q
What are the functions of the skeleton?
A
- Movement
- Support
- Protection of vital organs
- Calcium storage
- Haematopoesis
10
Q
What are the 2 ways in which bones develops “in utero”?
A
Intramembranous + endochondral
11
Q
What is intramembranous ossification?
A
• bone develops from fibrous membranes to
become mesenchymal cell template
• forms flat bones of skull, clavicle + mandible
12
Q
What is endochandral ossification?
A
- development of long bone from a hyaline cartilage model (first model)
- takes much longer than intramembranous ossification
13
Q
What are the 5 steps of endochondral ossification?
A
- bone collar formation
- cavitation
- periosteal bud invasion
- diaphysis elongation
- epiphyseal ossification
14
Q
What are the 4 main cells of bones?
A
- osteogenic
- osteocyte
- osteoblast
- osteoclast
15
Q
What are osteogenic cells?
A
bone stem cell
found in deep layers of periosteum
16
Q
Where can you find osteogenic cells?
A
deep layers of periosteum
17
Q
What are osteoblasts?
What do they do?
A
- bone forming
- secretes osteoid
- catalyse mineralisation of osteoid
18
Q
Where can you find osteoblasts?
A
growing portions of bone, including periosteum + endosteum
19
Q
What are osteoclasts? What do they do?
A
- bone breaking
- dissolve + reabsorb bone by phagocytosis
- derived from bone marrow
20
Q
Where can you find osteoclasts?
A
growing portions of bone, including periosteum + endosteum
21
Q
What are osteocytes?What do they do?
A
• mature bone cell • formed when osteoblast becomes embedded in its secretions • sense mechanical strain to direct osteoclast and osteoblast activity
22
Q
Where can you find osteocytes?
A
embedded in matrix
23
Q
What is bone matrix? How is it organised?
A
- 40% organic
* 60% organic
24
Q
What is the organic component of bone matrix made up of?
A
- 90% type 1 collagen
* 10% ground substance
25
What is the inorganic component of bone matrix made up of?
* calcium hydroxyapatite
| * osteocalcium phosphate
26
What is the ground substance of bone matrix made up of?
* proteoglycans
* glycoproteins
* cytokine + growth factors
27
What are the 2 types of bone?
* immature
| * mature
28
What is immature bone?
* first bone produced
* laid down in a ‘woven’ manner – relatively weak
* mineralised + replaced by mature bon
29
What is mature bone?
* mineralised woven bone
| * lamellar (layer) structure – relatively strong
30
What are the 2 types of mature bone?
* cortical
| * cancellous
31
What is cortical bone?
* compact + dense
| * suitable for the stresses of weight bearing
32
What is cancellous bone?
* spongy structure
| * not suitable for weight-bearing
33
What is an osteon?
* repeated structural units
| * concentric lamellae around a central Haversian Canal
34
How are cortical bones organised?
```
• Few spaces
• ‘Osteons’
• Haversian Canal –
contains blood vessels,
nerves and lymphaVcs.
• Lacunae – small spaces containing osteocytes
• Tiny canaliculi radiate
from lacunae filled w/
extracellular fluid
• Volkmans canal –
transverse perforating
canals
```
35
What is the structure of long bones?
* proximal epiphysis
* metaphysis
* diaphysis
* metaphysis
* distal epiphysis
36
What are the 2 methods of bone growth?
* interstitial
| * appositional
37
What is interstitial bone growth?
long bone lengthening (increasing length)
38
What is appositional growth?
deposition of bone
| beneath the periosteum to increase thickness (increasing width)
39
What are the 4 zones / steps in interstitial growth?
* proliferation
* hypertrophic/maturation
* calcification
* ossification
40
What is the importance of bone in increasing calcium serum levels?
→ Bone contains 99% of total body calcium
→ PTH stimulates calcium release from bone
→ osteoclasts activity > osteoblasts activity
41
What is the importance of bone in decreasing calcium serum levels?
m
42
What is the importance of calcium hydroxyapatite?
m
43
How are joints classified?
Fibrous (synarthrosis)
Cartilaginous (Amphiarthrosis)
Synovial (Diarthrosis)
44
What are the fibrous joints? Examples?
* Sutures
* Syndesmosis
* Interosseous membrane
45
What are cartilaginous joints? Examples?
* Synchondroses
| * Symphyses
46
What are synovial joints? Examples?
* Plane, Hinge, Condyloid
| * Pivot, Saddle, Ball & Socket
47
What is the structure of a synovial joint?
Joint capsule:
• Articular capsule (outer) keeps bones together structurally
• Synovial membrane (inner) - contains synovial fluid which reduces friction during movement
48
What factors affect joint stability?
* Joint shape e.g. hip vs shoulder
* Ligaments
* Tendons
* Cartilage (e.g. glenoid labrum)
49
What are ligaments made up of?
90% Type 1 collagen (strong)
| 9% Type 3 collagen (immature; greater in healing tissue)
1% fibroblast cells (produce collagen)
50
What is the function of a ligament?
Connect bone to bone to stabilise joint and enable proprioception '
51
What is collagen?
* Most abundant protein in the human body
* Molecule is a long, rigid structure
* 3 polypeptides (referred to as α chains) are wound around one another
* Rope-like triple helix
* Crimping of fibres
* Non-elastic behaviour
* Fibre component of connective tissue
52
What is a tendon?
* Made of collagen fibres arranged in bundles
* Stiff and Strong
* Parallel arrays of collagen fibres closely packed together
53
What is the microstructure of a tendon?
Parallel arrays of collagen fibres closely packed together
54
What is the function of a tendon?
* Attaches skeletal muscle to bone
* Transmits muscle force to bone
* Elastic energy storage/recoil
* Proteoglycan resists compressive stresses
55
What is cartilage?
* Made up of chondrocytes which produce large amounts of collagenous ECM, ground substance
* Avascular and worn down in osteoarthritis
56
What is the function of cartilage?
* Acts as shock absorber to reduce friction
* Covers and protects long bones at joints
* Structural component of ribs & intervertebral discs
57
What are the 3 types of cartilage?
Elastic Hyaline
| Fibrocartilage
58
How do ligaments affect joint stability?
* Ligaments prevent excessive movement that could damage joint
* More ligaments and tighter ligaments = greater stability BUT less mobility
* Less ligaments and laxer ligaments = greater mobility BUT less stability
59
What is the problem of poor stability in a joint?
Risk of dislocation
60
What is the problem with lax ligaments in joints?
Hypermobility = greater risk of injury
61
What is the problem w/ repeated or inappropriate stress to ligaments?
Increases risk of injury
62
What is periosteum?
dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints
63
What is a medullary cavity?
central cavity of bone shafts where red bone marrow and/or yellow bone marrow (adipose tissue) is stored
64
What is epiphysis?
end part of a long bone, initially growing separately from the shaft
65
What is metaphysis?
* neck portion of long bone between epiphysis + diaphysis
| * contains the growth plate
66
What is diaphysis?
shaft or central part of bone
67
What is step 1 of intramembranous ossification?
condensation of mesenchymal cells which differentiate into osteoblasts to form ossification centre
68
What is step 2 of intramembranous ossification?
secreted osteoid traps osteoblasts which become osteocytes
69
What is step 3 of intramembranous ossification?
trabecular matrix and periosteum form
70
What is step 4 of intramembranous ossification?
compact bone develops superficial to cancellous bone + crowded blood vessels develop into blood vessels
71
Where is the primary ossification centre?
diaphysis
72
Where is the secondary ossification centre?
epiphysis
73
What is the proliferation zone in interstitial growth?
cells proliferate + push epiphyses away from diaphysis
74
What is the hypertrophic / maturation zone in interstitial growth?
* cartilage cells swell in size (called hypertrophy)
* lacunae get larger
* results in the formation of large spaces
75
What is the calcification zone in interstitial growth?
* cartilage is calcified at the juncture of diaphysis + epiphyses
* matrix breaks down
* blood vessels enter the spaces
76
What is the ossification zone in interstitial growth?
* marrow from medullary cavity enters calcified cartilage
| * osteoclasts break down cartilage + osteoblasts replace it with new spongy bone
77
What is the epiphyseal plate?
zone of elongation in long bones, contains hyaline cartilage
78
What zones or steps of interstitial growth are on the epiphyseal side?
* proliferation
| * hypertrophy
79
What zones or steps of interstitial growth are on the diaphyseal side?
* calcification
| * ossification
80
What is step 1 of appositional growth?
ridges in the periosteum create a groove for
| periosteal blood vessel
81
What is step 2 of appositional growth?
periosteal ridges fuse, forming an endosteum-lined tunnel
82
What is step 3 of appositional growth?
osteoblasts in endosteum build new concentric
| lamellae inward towards the centre of the tunnel, forming a new osteon
83
What is step 4 of appositional growth?
bone grows outwards as osteoblasts in periosteum build new circumferential
lamellae. Osteon formation repeats as new periosteal ridges fold over blood vessel
